Hi DEVPOM1234,

Thanks for reaching to us.

Please add the below Custom CSS code to Theme Settings > Custom CSS > Global Custom CSS for Mobile sections:

ul.wd-nav-mob-tab>li>a {
    background-color: #000;
}

ul.wd-nav-mob-tab>li.wd-active>a {
    background-color: #fff;
}

Regards,